Hydraulic punch and stripper



8= 1956 c. E. NOVINGER ETAL HYDRAULIC PUNCH AND STRIPPER 5 Sheets-Sheei 1 Filed Dec. 7, 1955 Nmfi w mm m m% Q g mm K) L 1 E QT w 7 m om x Om Fl .wm 9 wm I. Q Q

wm w CECIL arrow/5r 5 heSheet 2 c. E. NOVINGER EI'AL HYDRAULIC PUNCH AND STRIPPER Filed Dec. 7, 1955 I a INVENTORS CECIL E. Wow/1166B ATTORNEY Aug. 14, 1956 C. E. NOVINGER ETAL HYDRAULIC PUNCH AND STRIFPER Filed Dec. 7, 195;

s Sheets-Sheet 5 Zk/w g8 #32 j we 7 INVENTORS F-LS 650A 6'. A/Ol/l/VG-EE BY L I 5 ATTORNEY United States Patent HYDRAULIC PUNCH AND STRIPPER Cecil E. Novinger, La Grange, 11]., and Otto Mueller,

Dear-born, Mich, assignors to Danly Machine Specialties, Inc., Chicago, 111., a corporation of Illinois Application December 7, 1953, Serial No. 396,693

8 Claims. (Cl. 164-95) Our invention relates to a hydraulic punch and stripper and more particularly to an improved hydraulic punch and stripper which is adapted to eject slugs from a die button when a punch is used to punch from the inside outward of a piece part.

When a punch is used to perforate a piece of work or to form a piece part, it is desirable that the Work be held with reference to the punch so that the part will not be distorted or the work broken out when the punch is withdrawn. A hydraulic punch and stripper device for performing this operation has been disclosed in Patent No. 2,534,292, issued December 19, 1950, to Otto Mueller. The device there shown includes a cylinder body formed with a power chamber which houses a power piston and a stripper chamber housing a stripper piston. The power piston cooperates with the cylinder to perform the punching while the stripper piston is adapted to be actuated during the return stroke of the punching cycle to hold a pressure plate against the face of the work While the punch is being stripped by the power piston. Generally, the cylinder body is slidably mounted on a fixed power piston and carries the punch through the work. The die is held fixed relative to the cylinder and its recess is continued back through the die button so that slugs or piece parts formed during the punching operation are forced back through the recess to drop into a suitable container. Any convenient valve means is employed to supply fluid under pressure to the respective power and stripper chambers to perform the punching and stripping operations in the proper sequence.

It is, however, often necessary to punch from the inside outwardly of a piece part, such as, for example, a shroud ring, in order that the rough edge of the opening punched in the work will appear on the outside surface of the ring. When punching from the inside out there is generally insuificient space inside the ring to accommodate the structure of the cylinder carrying the punch. Consequently, this cylinder must be placed outside the work, and since we desire to punch from the inside out, the die button must be mounted on the cylinder body and the punch disposed inside the ring. When the die button is thus carried by the cylinder, slugs cannot be ejected back through the die recess, since in this case they would interfere with and jam the stripper piston.

We have invented an improved punch and stripper cylinder which is provided with means whereby a slug or piece part formed in the die during a punching operation may be automatically ejected from the die at the end of a punching operation. Our cylinder is adapted, moreover, to be used as a knockout to knock the work out of the die when a shallow forming operation rather than punching operation is to be performed. This latter feature eliminates the necessity of employing a positive bar knockout which operates knockout pins in the dies to actuate a stripping plate in a mechanical press. That is, we have invented an improved punch and stripper cylinder which is capable of performing both the functions of ice stripping the punch from the work and ejecting slugs or knocking work out of the die.

One object of our invention is to provide an improved punch and stripping device which is capable of performing both the functions of stripping the punch from the work and ejecting slugs or pic 2e parts from the die button.

Another object of our intention is to provide an improved punch and stripper cylinder which is particularly adapted for punching from the inside out of a piece part.

A further object of our invention is to provide an improved punch and stripper cylinder which can be employed as a knockout in the event a shallow forming operation is to be performed.

A still further object of our invention is to provide an improved punch and stripper cylinder which can be selectively arranged to perform its normal operation of stripping or which may be used to perform both the operations of stripping and of ejecting slugs from the die button.

Other and further objects of our invention will appear from the following description.

in general, our invention contemplates the provision of a C-frame having a pair of arms slidably mounted in ways formed on a suitable work table. A first arm of the C-frame is fixed to the power piston of our improved punch and stripper assembly and is adapted to be driven thereby. The other arm of the C-frame supports the punch. The cylinder of our improved punch and stripper assembly includes a power side or chamber in which the power piston is mounted for reciprocation and a stripper side or chamber in which we mount a stripper piston. The stripper side of the cylinder body mounts a housing to which the die button of the assembly is fixed. We mount a knockout plunger for sliding movement within the housing in a position where it is engaged and actuated by the stripper piston. The plunger is formed with a pin for movement into the die button recess to knock out a slug or piece part when the plunger is actuated by the stripper cylinder.

The power piston of our assembly is provided with a pair of bores forming pressure lines, each communicating with the power chamber of the cylinder on a respective side of the power piston. Fluid under pressure is successively admitted to one and then the other of the pair of pressure lines to cause the cylinder, carrying the die button, and the power piston, driving the C-frame which carries the punch, to reciprocate relative to one another first to perform the punching operation and then to return the parts to the starting position. The work is, of course, disposed between the punch and die so that the die button is first moved into engagement with the work and then the punching operation is performed. When the punching operation is completed, a supply valve is reversed to supply pressure to the power piston pressure lines in a direction to strip the punch from the work and return the parts to their initial position.

In order to supply fluid under pressure to the stripper side of the cylinder at the proper time in the punching cycle, we provide the cylinder body with passageways adapted to connect the stripper chamber to the pressure line which serves as an exhaust passage during the punch ing phase and to which fluid pressure is admitted during the return phase of the operation. interposed between these passageways is a control valve which is open during the punching phase. This control valve is initially closed during the return phase by suitable means such as a spring but is actuated at the point in the return portion of the cycle at which the knockout operation is to be performed in order to supply fluid under pressure to the stripper side of the cylinder. When this connection is made, the stripper piston actuates the knockout plunger to move its pin into the die button recess and knock a slug or piece part out of the die button recess. Adjustable means fixed on the work table actuates the control valve. When the knockout operation is completed, the work is stepped around angularly and the supply valve again reversed to perform the next punching operation. The arrangement of our improved punch and stripper assembly is such that, if desired, the punch and stripper assembly may be operated in a conventional manner to perform only the stripping function.

In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

Figure 1 is a top plan view of our improved punch and stripper assembly mounted on a suitable work table and showing its relationship to the work.

Figure 2 is a sectional view of our improved punch and stripper assembly taken along the line 22 of Figure 1.

Figure 3 is a sectional view on an enlarged scale of a portion of our apparatus.

Figure 4 is a side elevation of a portion of our apparatus with parts in section showing the relative position of the parts immediately after a slug has been ejected from the die button.

Figure 5 is a view similar to Figure 4 showing the relative position of the parts just before a punching operation begins.

Figure 6 is a view similar to Figure 4 showing the relative position of parts near the end of the punching stroke.

Figure 7 is a view similar to Figure 4 showing the relative position of parts at the beginning of the return stroke.

More particularly, referring now to Figures 1 and 2, a work table 10 has a ring bearing 12 mounted thereon which supports, for rotary movement, a work holder 14 to which is fixed a ring gear 16 by means of bolts 18. Ring gear 16 is engaged by a drive gear 20 fixed on a shaft 22 which is driven by an appropriate indexing mechanism 24 known to the art. A motor 26, having electrical connections 28, provides a drive means for driving indexing mechanism 24. A base supports indexing mechanism 24 and motor 26 and is mounted on a bracket 32 supported from the table by any appropriate means (not shown). Suitably formed clamps 34 are screwed to work holder 14 by screws 36 to hold the work 38 in position, as can be seen by reference to Figures 1 and 2. The indexing mechanism 24 provides a means by which the work can be stepped around with relation to the punch and stripper assembly to be described. A pair of slots 44 and 45 in the surface of the table 10 open into a guideway 40 formed below the surface of the table 10. We mount a C-frame, indicated generally by the reference character 42, for reciprocation along guideway 40 so that the respective arms 46 and 48 of C-frame 42 extend upwardly through slots 44 and 45, It will be appreciated that in order to permit assembly of C-frame 42 in the guideway 40, the portion 47 of the table 10 separating the slots 44 and 45 may be made removable by any suitable means (not shown). Portion 47 of table 10 may also be provided with an upward extension 49 provided with a guideway 51 to support the cylinder assembly, which will be described hereinafter, for sliding movement.

Arm 46 of C-frame 42 carries a fitting by means of screws 52. A punch holder 54, which is adapted to hold a punch 56, is threaded into fitting 50. Punch 56 is removably held in punch holder 54 by any appropriate means, such as a force fit, well known in the art.

Arm 48 of C-frame 42 supports power piston 58' of the punch and stripper assembly by any appropriate means, such as screw threads 60; The cylinder body, indicated generally by reference numeral 62, includes a power side or chamber 64- and a stripper sideor chamher 66. The head 68 of piston 58 is slidably mounted within the power side 64 of cylinder 62 which is closed by a cap 70 to retain pistonhead 68 therein. The stripper chamber 66 and power chamber 64 are separated by an annular inwardly extending flange 72 in the opening of which we mount a plug 74 and provide a nut 76 for holding the plug in place. A pin 78 is mounted for reciprocating movement in a bore 80 formed in the plug 74. A stripper piston 82 is 'slidably mounted within the stripper chamber 66 of cylinder 62 and has a bore 84 carrying a pin 86.

The die holder assembly, indicated generally by reference character 88, is fixed on the end of the stripper side 66 of cylinder 62 by bolts attaching a first collar 92 to cylinder 62. A cylindrical member 94 is disposed within the bore of collar 92 and retained in position within the bore by a second collar 96 attached to the first collar 92 by bolts 98. An annular flange 100 on member 94 cooperates with a shoulder 182 formed in the bore of collar 92. A second cylindrical member 104 is disposed within the bore of collar 96 and cooperates with cylindrical member 94 to form a housing for the knockout plunger, indicated generally by the reference character 106. A die button 108 is carried by a pair of threaded studs 110 screwed into the end of member 104. Die button 138 and member 104 are retained in position with respect to collar 96 by a special cap nut 112 threaded within the bore of collar 96. An inwardly extending annular flange 114 on nut 112 cooperates with shoulder 116 formed on the die button. The knockout plunger 1% includes a body portion 118 having bifurcations 120 formed at one end thereof and a rod or pin 122 extending from the other end. It will be appreciated that body portion 118 is mounted for sliding movement within the housing formed by members 94 and 104 and that rod or pin 122 extends through an opening 124 formed in the end of member 104 and into the recess of die button 108. A bar 126 is mounted by bolts 128 on member 94 between the bifurcations 129 of knockout plunger 106. This bar is provided to immobilize pins 36 78 for reasons which will be explained in detail hereinafter.

A suitable valve of a type known in the art but not shown supplies fluid pressure for actuating the cylinder and piston assembly to perform the punching, stripping, and knocking out operations. Referring now to Figures 2 and 3, power piston 53 is provided with a first bore forming a first pressure line 130 for supplying fluid under pressure from the supply valve to the power chamber 64 of cylinder 62 during the punching phase of the operation. It will be appreciated that when fluid pressure is applied through passageway 130, cylinder 62 and pistonhead 63, carried by the Cframe 42. move relative to one another to move the die button 108 into engagement with the work and drive punch 56 through the work by moving the C-frame to the right. A second bore forming a second pressure line 132 is provided in piston 58 for supplying fluid pressure to perform the stripping, return, and knocking out operations. It will readily be understood that when one of the lines 130 or 132 is connected to a source of fluid under pressure, the other line 132 or 13% serves as a return line- A passageway 134 connects line 132 to power chamber 64 on a side of head 68 such that when pressure is supplied through line 132, the C-frame 42 and cyhnder 62 tend to move relative to one another in a direction opposite to the direction in which they move punching operation to drive it out of the die button.

eagerness- The valve assembly for controlling the'knocking out action of plunger 106 is indicated generally by the reference character 144 and 1116113165 a housing 146 in which we slidably mount a plunger 148 formed with a valve head 150. Plunger 148 is normally urged to the right as viewed in Figure 3 by a spring 152 bearing between one end of the valve chamber 154 and the valve head 150. Spring 152, therefore, normally urges head 150 in a direction'to engage a seat 156 formed in chamber 154. Line 136 com- 'municates with valve chamber 154 by a passageway 158 in the wall of housing 146. 'A second valve chamber 160 formed on the side of head ISO-removed from chamber 154 communicates through a passageway 164 with a line 162 formed in the body of cylinder 62 and leading to stripper chamber 66. As can be seen by reference to Figures 2 and 3, when the valve head 150 is in the position shown, chamber 160 communicates with chamber 154 through openings 166. An adjustable stop 168 is fixed with reference to the work table and is adapted to actuate plunger 148 to move it from a closed position to the position shown when the cylinder 62 carrying valve 144 occupies a predetermined position in the return stroke of the operational cycle.

Line 162 opens into the stripper side 66 of cylinder 62 so that when fluid under pressure is admitted to line 162 by valve 144, piston 82 is driven to the left as viewed in Figures 2 and 3. Bifurcations 120 of plunger 106 bear against piston 82 so that when the piston is moved to the left, the plunger 106 moves to the left within the housing formed by members 94 and 104 and pin 122 engages the slug or piece part in the die button formed during the Such a slug is indicated in the drawings by reference character 170. In the event we desire to use the assembly in the ordinary manner to perform the stripping function, we 'may deactivate the valve by any suitable means such as a screw engaging plunger 148 to prevent its movement.

Referring now to Figure 1, we provide collar 92 of die holder assembly 88 with a pair of lateral wings 172 and 174, each of which carries a respective stop screw 176 and 178 held in position by nuts 180 and 182. It will be appreciated that stop screws 176 and 178 are adjustable and cooperate, respectively, with stops 184 and 186 fixed to the work table by any appropriate means such as welding or the like to limit the movement of cylinder 62 to the right as viewed in Figure 1 so that the die button is nearer to the work than is the punch at the beginning of a punching cycle.

The operation of our improved punch and stripper cylinder assembly can best be understood by reference to Figures 4 to 7, which illustrate the positions of the punch and die at successive stages of the punching operation. The positions of the elements making up the assembly after knockout and before a punching operation is commenced are shown in Figure 4. The power pistonhead 68 is at its furthest position within the power chamber 64 of cylinder 62, and the stripper piston 82 is in its outermost position in the stripper chamber 66 of cylinder 62. To initiate the punching operation, line 130 is connected to the source of fluid pressure, and line 132 is connected to the're'turn side of the supply valve. Fluid entering through line 130 tends to force piston 68 and cylinder 62 away from each other; that is, it tends to force cylinder 62 to the left as shown in Figure 5 and pistonhead 68' to the right. The result of this application of pressure to line 130 will be a movement of the cylinder 62 to the left as viewed in Figure 5 to bring die button 108 into engagement with the work 38. After the cylinder 62 has moved to the left, its further movement will be prevented by the engagement of die 108 with the work 38, and piston 68 drives the C-frame 42 and punch 56 to the right. During this movement of the cylinder 62 and piston 68 relative to one another, the return side of piston 68 is connected to return line 132 by passageways 134 and 140. As the punch 56 moves through the work, it

formsaslug or piece part l70 and-pushes it into engage- -ment with rod 122 of plunger 106. Upon further movement of the punch, plunger 106 is moved to the right, and by virtue of the engagement of its bifurcations with stripper piston 82, it pushes the stripper piston 82 back into the stripper chamber 66 of cylinder 62. This stage ofthe operation is illustrated in Figure 6. As will be apparent from an examination of Figure 6, fluid from chamber 66 will be forced through passage 162 into chamsolid member without a pin 86. It will be appreciated that in such an assembly when pressure is applied to line 130, it would move pin 78 to the left, as viewed in the drawings, to force the stripper piston 82 to the left. That is, it would initiate a movement of piston 82 to eject a slug by means of plunger 106 before the punch has been stripped .from the work. To obviate this result, we provide piston 82 with pin 86 and arrange bar 126 to prevent any movement of pin 78 when pressure is applied through line 130. It is to be understood that our cylinder and piston assembly could be arranged to operate in a conventional manner merely by employing a conventional arrangement so that the movement of pin 78 is not blocked by means such asbar 126 and by maintaining valve 150 open.

When the punching operation has been completed, the supply valve is reversed so that line 132 is connected to the supply side of the valve. Line 130 is connected to the return side of the supply valve and the die button -moves away from the work. This connection of lines 130 and 132re'sult's in a movement of the cylinder assembly carrying die button 108 to the right and a movement of punch holder 54 to the left as viewed in Figure 7.

When the return cycle is initiated, there is no more exhaust pressure from stripper chamber 66 so that spring 152 closes valve 150. Since this valve is closed, fluid under pressure from line 132 cannot actuate the stripper piston 82.

After line 130 has been connected to the return side of the supply valve, cylinder 62 moves to the right until rod 168 engages plunger 148 to open the valve 150. This permits pressure to be applied to the stripper piston through line 136, the valve chambers 154 and 160, and line 162. Rod 168 is adjusted to a position such that it engages plunger 148 to open the valve. The application of pressure to piston 82 forces the piston to the left as viewed in Figure 4 and, by virtue of the engagement of the piston with bifurcations 120, forces knockout plunger 106 to the left. Pin 122 thereby engages the slug 1'70 and pushes it out of the die button as shown. The relative position of the elements of the piston and cylinder assembly are then as shown in Figure 4, and the supply valve may be reversed to initiate another punching operation. Stops 184 and 186 limit the movement of cylinder 62 away from the work during the return stroke and cause movement of C-frame 42 and punch 56 to the left.

While we have shown our punching die as being adapted merely to punch a hole in a work piece, it will be appreciated that any form punch and die could be employed. For example, if the die were employed in a shallow forming job, the knockout plunger 106 could be used to knock the Work out of the die. It will be appreciated also that were such a shallow forming job to be done, the stripper piston and cylinder would act as a cushion to give the eflect of a double action press operation, when the Work pushed plunger 106 to drive piston 82 into the stripper chamber 66 and exhaust the chamber against the action of spring 152 of valve 150. That is, when the punch moves against the die, pin 122 or its equivalent would be cushioned by the stripper piston 82 so as to give relative to thedie. It would then be actuated after punching was completed to knock the work out of the die.

Thus it will be seen that we have accomplished the objects of our invention. We have provided an improved hydraulic punch and stripper which is adapted to perform two functions. It operates to strip the punch from the work and also acts as a knockout to, eject slugs or piece parts from the .die. In. addition, as explained, it may be used when shallow forming is to be done to give the effect of a double action press, and when so used, it also acts to knock the work out of the die. Our improved punch and stripper is particularly adapted for use when punching from the inside out of a piece part.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. It is therefore to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, what we claim 1. A hydraulic punch and stripper assembly including in combination a cylinder body formed with a power chamber and a stripper chamber, a power piston mounted for reciprocation within said power chamber, a stripper piston mounted for reciprocation in said stripper chamber, a die carried by said cylinder body, a punch, means mounting said punch on said power piston for cooperation with said die, means for supplying fluid pressure to the power chamber to move said power piston and cylinder body relative to one another to perform a punching operation, a knockout plunger slidably mounted on the cylinder body, said plunger being formed with a portion adapted to extend into said die, said plunger being in engagement with said stripper piston and means for admitting fluid under pressure to said stripper chamber at a predetermined point on the operational cycle of the assembly after said punching operation whereby said stripper piston moves said plunger portion into the die.

2. A hydraulic punch and stripper assembly as in claim 1 wherein said power piston is formed with a pair of fluid conduits leading to the respective sides of said power piston and said means for supplying fluidpressure to said stripper piston includes a pair of passageways and a valve interposed between said passageways, one of said passageways being connected to one of said fluid conduits and the other of said passageways being connected to said stripper chamber.

3. A hydraulic punch and stripper assembly as in claim 1 wherein said cylinder body is formed with a partition dividing the body into said power and stripper chambers, a pin slidably mounted in said partition and extending between the power and stripper chambers and means for immobilizing said pin.

4. A hydraulic punch and stripper assembly as in claim 1 including adjustable stop means for limiting the movement of the cylinder body away from the work.

5. A hydraulic punch and stripper assembly including in combination a work table, a C-frame slidably mounted in said table and having a pair of arms, a cylinder body formed with a power chamber and a stripper chamber, a power piston fixed to one of said arms and disposed for reciprocation within saidpower chamber, a die fixed to the end of said cylinder body adjacent the stripper chamber, a punch, means mounting said punch on the other of said arms for cooperation with said die, means for alternately applying fluid under pressure to the power chamber adjacent the respective sides of said power piston to cause relative movement between said cylinder body and said C-frame whereby a punching operation is performed, a knockout plunger slidably carried by the cylinder body and formed with a portion adapted to extend into said die, a stripper piston mounted for movement within said stripper chamber and adapted to engage said plunger and means for admitting fluid under pressure to said stripper chamber at a predetermined point in the operational cycle of the assembly after said punching operation.

6. A hydraulic punch and stripper assembly including in combination a cylinder body having a power chamber and a stripper chamber, a power piston mounted within said power chamber, a first conduit for supplying fluid under pressure to said power chamber adjacent one side of said power piston, a second conduit for supplying fluid under pressure to said power chamber adjacent the other side of said power piston, said conduits being alternately supplied with fluid under pressure to relatively reciprocate said power piston and said cylinder body, a die carried by said cylinder body, a punch, means mounting said punch on said power piston for cooperation with said die, the arrangement being such that said die cooperates with said punch to perform a punching op eration when said power piston and said cylinder body relatively reciprocate, a stripper piston disposed within said stripper chamber, means for supplying fluid under pressure to said stripper chamber to actuate said stripper piston at a predetermined point during the operational cycle after said punching operation of the machine and knockout means actuated by said stripper piston to enter said die.

7. A hydraulic punch and stripper assembly as in claim 6 wherein said means for supplying fluid under pressure to said stripper chamber comprises fluid sup ply conduits formed in said cylinder body, a valve interposed in said supply conduits, and means for actuating said valve at a predetermined point during the return stroke of said assembly.

8. A hydraulic punch and stripper assembly as in claim 6 including a die button assembly forming a knockout plunger housing and wherein said means actuated by the stripper piston comprises a knockout plunger mounted in said housing.

References Cited in the file of this patent UNITED STATES PATENTS 247,465 Long Sept. 20, 1881 1,625,748 Schiess Apr. 19, 1927 1,710,592 Seavey Apr. 23, 1929 2,173,358 Ernst Sept. 19, 1939 2,280,849 Pocock Apr. 28, 1942 2,674,311 Griswold Apr. 6, 1954 

